Wiring substrate

ABSTRACT

A wiring substrate includes a wiring board having a main face and a side face substantially perpendicular to the main face; a circuit pattern which is formed on the main face of the wiring board; a soaking plate which is disposed in an intermediate layer of the wiring board; and a plurality of protruding terminals are disposed in the intermediate layer and are projected outwardly from the side face. The protruding terminals are electrically connected in the intermediate layer to each other.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a Divisional Application of U.S. application Ser. No. 13/147,961filed Aug. 4, 2011 which is a National Stage Application ofPCT/JP2010/057844 filed Apr. 27, 2010, which claims priority fromJapanese Patent Application No. 2009-107746 filed Apr. 7, 2009. Theentire disclosures of the prior applications are hereby incorporated byreference.

TECHNICAL FIELD

The present invention relates to a wiring substrate including a soakingplate and a manufacturing method of the wiring substrate, andparticularly to a technique for reducing electric wires for connectingterminals on a face of the wiring substrate.

BACKGROUND ART

For example, a wiring substrate installed in an electrical distributionbox of a vehicle uses the wiring substrate configured to dispose a metalplate (soaking plate or heat dissipation plate) in an intermediate layerof the wiring substrate in order to avoid a local increase intemperature by heat generation of an electronic component (for example,see PTL 1). By using such a metal plate, the heat generated in theelectronic component is diffused in the whole wiring substrate and thusa heat dissipation effect is promoted, so that damage to a circuitpattern and the electronic component by the local increase intemperature can be prevented.

FIGS. 10 and 11 are explanatory diagrams showing a configuration of arelated wiring substrate 110, and FIG. 10 shows a surface layer and FIG.11 shows an intermediate layer (that is, an inside layer excluding thesurface layer), respectively. As shown in FIG. 11, a metal plate 111having conductivity is disposed in substantially the center of theintermediate layer of the wiring substrate 110. Also, a plurality ofprotruding terminals 112 (12 pieces in the drawings) having rectangularshapes are respectively disposed in the left lateral side part and theright lateral side part of the wiring substrate 110, and a part of eachof the protruding terminals 112 protrudes toward the outside of thewiring substrate 110. Then, when a connector (not shown) is connected tothe wiring substrate 110, this protruding portion can be used as aterminal for connector connection.

Also, as shown in FIG. 10, a prepreg 131, which is an insulatingmaterial, is disposed on a face of the wiring substrate 110 and thesurface layer is formed. On this surface layer, various electroniccomponents 115 are installed and a circuit pattern 114 is cabled.Further, in order to connect the circuit pattern 114 disposed in thesurface layer to the protruding terminals 112 disposed in theintermediate layer, through holes 113 are bored in at least one of theplural protruding terminals 112 (see FIG. 11). That is, the protrudingterminals 112 can be electrically connected to the circuit pattern 114via the conductive through holes 113.

Also, for example, in the case of electrically connecting three throughholes 113-1, 113-2, 113-3 shown in the upper left of FIG. 10, it isnecessary to provide circuit patterns 114-1, 114-2 for making connectionbetween each of the through holes 113-1, 113-2, 113-3 on the surfacelayer of the wiring substrate 110. The circuit patterns 114 formed onthe surface layer of the wiring substrate 110 increase and a problem ofreducing space for arranging the electronic components by the increasedcircuit patterns arises.

CITATION LIST Patent Literature

[PTL 1] JP-A-2007-281138

SUMMARY OF INVENTION Technical Problem

As described above, in the related wiring substrate 110, the pluralprotruding terminals 112 are formed in the same layer as the metal plate111, and the through holes 113 are disposed in at least one of theprotruding terminals 112, and the circuit patterns 114 formed on thesurface layer are connected to the protruding terminals 112 via thethrough holes 113. Then, in the case of making electrical connectionbetween the plural protruding terminals 112, it is necessary to form thecircuit patterns 114 (114-1, 114-2, etc. shown in FIG. 10) on thesurface layer of the wiring substrate 110, so that there is adisadvantage in that space on the wiring substrate 110 cannot be usedeffectively, and the demand that the space on the wiring substrate 110want to be effectively utilized is increasing.

The invention has been implemented to solve such a related problem, andan object of the invention is to provide a wiring substrate including asoaking plate capable of effectively utilizing space an the wiringsubstrate by reducing a circuit pattern disposed in a surface layer ofthe wiring substrate, and a manufacturing method of the wiringsubstrate.

In order to achieve the above object, according to the presentinvention, there is provided a wiring substrate, comprising:

-   -   a wiring board that has a main face and a side face        substantially perpendicular to the main face;    -   a circuit pattern that is formed on the main face of the wiring        board;    -   a soaking plate that is disposed in an intermediate layer of the        wiring board; and    -   a plurality of protruding terminals that are disposed in the        intermediate layer and are projected outwardly from the side        face,    -   wherein the protruding terminals are electrically connected in        the intermediate layer to each other.

Preferably, the wiring substrate further includes other protrudingterminal that is disposed in the intermediate layer and is projectedoutwardly from the side face, the other protruding terminal is separatedfrom the plurality of protruding terminals.

Preferably, a through hole for electrically connecting the protrudingterminals to the circuit pattern is communicated from the main face tothe intermediate layer.

Preferably, the soaking plate, which is comprised of a conductivematerial, is electrically connected to the circuit pattern.

According to the present invention, there is also provided a method formanufacturing a wiring substrate, comprising:

-   -   processing a metal flat plate in a shape of a plurality of        protruding terminals and a soaking plate; and    -   forming a resin layer on at least one of a front side and a rear        side of the metal flat plate having the protruding terminals and        the soaking plate so that a part of each of the protruding        terminals protrudes to the outside of the resin layer,    -   wherein in the processing process, the protruding terminals are        processed so as to be mutually connected in the resin layer.

Preferably, the method further includes: forming a through hole, whichis communicated from a surface of the resin layer to a part of theprotruding terminals, in the resin layer.

Advantageous Effects of Invention

By the above configuration, the plural protruding terminals disposed inthe intermediate layer are mutually connected, so that it is unnecessaryto form the circuit pattern for connecting the protruding terminals onthe main face and the circuit pattern on the main face can be reduced.As a result, space of the main face can be utilized effectively and thespace for installing various electronic components can be obtainedwidely.

By the above configuration, when the through hole is formed from themain face to the intermediate layer and the protruding terminals areconnected to the circuit pattern disposed on the main face via thethrough hole, the number of through holes can be reduced and the spaceof the main surface of the wiring substrate can be utilized effectively.

By the above configuration, the soaking plate (metal plate) is used as aconductor and is connected to the circuit pattern, so that connectionbetween the circuit pattern and the soaking plate can easily be made byusing the soaking plate.

By the above method, the soaking plate and the protruding terminals canbe fabricated in the same step, so that the wiring substrate can bemanufactured by a simple procedure.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is an explanatory diagram showing a configuration of a surfacelayer of a wiring substrate according to an embodiment of the invention.

FIG. 2 is an explanatory diagram showing a configuration of anintermediate layer of the wiring substrate according to the embodimentof the invention.

FIG. 3 is an explanatory diagram showing a procedure for fabricating thewiring substrate according to the embodiment of the invention, and showsa step of processing a metal plate.

FIG. 4 is an explanatory diagram showing a procedure for fabricating thewiring substrate according to the embodiment of the invention, and showsa step of laminating a prepreg.

FIG. 5 is an explanatory diagram showing a procedure for fabricating thewiring substrate according to the embodiment of the invention, and showsa step of forming a through hole.

FIG. 6 is an explanatory diagram showing a procedure for fabricating thewiring substrate according to the embodiment of the invention, andshowing a step of forming a circuit pattern.

FIGS. 7A and 7B are explanatory diagrams showing procedures forfabricating the wiring substrate according to the embodiment of theinvention, and showing a step of cutting a rib and forming the finalwiring substrate.

FIG. 8 is a flowchart showing a procedure for fabricating the wiringsubstrate according to the embodiment of the invention.

FIG. 9 is an explanatory diagram showing a modified example of thewiring substrate according to the embodiment of the invention.

FIG. 10 is an explanatory diagram showing a configuration of a surfacelayer of a related wiring substrate.

FIG. 11 is an explanatory diagram showing a configuration of anintermediate layer of the related wiring substrate.

DESCRIPTION OF EMBODIMENTS

An embodiment of the invention will hereinafter be described based onthe drawings. FIG. 1 is an explanatory diagram showing a surface layerof a wiring substrate 10 according to one embodiment of the invention,and FIG. 2 is an explanatory diagram showing an intermediate layer (thatis, a layer excluding the surface layer).

As shown in FIG. 2, a rectangular metal plate (soaking plate or heatdissipation plate) 11 is disposed in substantially the center of theintermediate layer of the wiring substrate 10. The metal plate 11 ismade of a metallic material and has conductivity.

Also, a plurality of protruding terminals 12 (12 pieces in the drawings)having rectangular shapes are respectively disposed in the left lateralside part and the right lateral side part of the wiring substrate 10,and a part of each of the protruding terminals 12 protrudes to theoutside of the wiring substrate 10. Then, when a connector (not shown)is connected to the wiring substrate 10, the protruding portions of theprotruding terminals 21 can be used as a terminal. In addition, when itis necessary to individually distinguish each of the protrudingterminals 12, each of the protruding terminals 12 is represented byassigning a suffix “-n”.

Some of the protruding terminals 12 are mutually connected through jointportions 16. Concretely, the protruding terminals 12-1, 12-2, 12-3 shownin FIG. 2 are mutually connected by the joint portions 16 and theprotruding terminals 12-4, 12-5 are mutually connected by the jointportion 16 and further, the protruding terminals 12-6, 12-7 are mutuallyconnected by the joint portion 16.

As shown in FIG. 1, a prepreg 31, which is an insulating material, isdisposed on a face of the wiring substrate 10 as a surface layer of thewiring substrate 10. On the surface layer, various electronic components15 are mounted and a circuit pattern 14 is also formed. Also, in orderto connect the circuit pattern 14 disposed on the face of the wiringsubstrate 10 to the protruding terminals 12 disposed in the intermediatelayer, through holes 13 are formed in at least one of the pluralprotruding terminals 12 (see FIG. 2). That is, the protruding terminals12 can be electrically connected to the circuit pattern 14 formed on thesurface layer via the conductive through holes 13.

In this example, the through hole 13 is formed in only one protrudingterminal 12-3 of the three protruding terminals 12-1, 12-2, 12-3, andthe through hole 13 is not formed in the other protruding terminals12-1, 12-2. Similarly, the through hole 13 is formed in only oneprotruding terminal 12-4 of the two protruding terminals 12-4, 12-5, andthe through hole 13 is formed in only one protruding terminal 12-6 ofthe two protruding terminals 12-6, 12-7.

That is, in the related wiring substrate 110 shown in FIGS. 10 and 11,each of the protruding terminals 112 disposed in the intermediate layeris respectively separated, so that it is necessary to form the circuitpatterns 114-1, 114-2 (see FIG. 10), etc. on the surface layer in orderto electrically connect these protruding terminals 112, but in theembodiment, the three protruding terminals 12-1, 12-2, 12-3 areconnected in the intermediate layer by the joint portions 16 as shown inFIG. 2, so that it is unnecessary to form the through holes 13 in allthe three protruding terminals 12-1, 12-2, 12-3 and it is unnecessary toform the circuit pattern for connection on the surface layer.

Therefore, as shown in FIG. 1, the circuit pattern 14 formed on thesurface layer can be reduced and accordingly, more electronic components15 can be disposed on the wiring substrate 10.

Next, a procedure for manufacturing the wiring substrate 10 mentionedabove will be described with reference to explanatory diagrams shown inFIGS. 3 to 7B and a flowchart shown in FIG. 8. In addition, in theexplanatory diagrams shown in FIGS. 3 to 7B, the number of protrudingterminals 12 is set at five pieces in the right and left sides in orderto simplify the explanation.

First, a metal plate 25 used as material of the metal plate 11 and theprotruding terminals 12 is processed in a shape as shown in FIG. 3 byetching or press processing (step S1 of FIG. 8; first step). Concretely,the rectangular metal plate (soaking plate) 11 and the protrudingterminals 12 respectively disposed five by five in the right and leftsides are formed and further, the joint portions 16 for connecting theprotruding terminals 12-11, 12-12, 12-13 are formed and the jointportions 16 for connecting the protruding terminals 12-14, 12-15 areformed. In addition, in the example shown in FIG. 3, a configuration ofseparating the metal plate 11 and each of the protruding terminals 12 isadopted, but a configuration of connecting the metal plate 11 and atleast one protruding terminal 12 can also be adopted according to useapplication as described below.

Next, as shown in FIG. 4, the prepreg (resin layer) 31 including metalfoil is laminated on one face or both faces of the metal plate 25 andthe prepreg 31 is heated and pressed o form an external shape of thewiring substrate 10 (step S2; second step).

As shown in FIG. 5, the through holes 13 for connecting a face of theprepreg 31 to the desired protruding terminals 12-13, 12-15 are formed,and further the through holes 13 are plated to make an electricalconduction state (step S3).

Thereafter, a circuit pattern is masked on the face of the prepreg 31and is etched to form the desired circuit pattern 14 (step S4). As aresult of this process, the wiring substrate 10 having the circuitpattern 14 and the through holes 13 is formed as shown in FIG. 6.

Then, as shown in a plan view of FIG. 7A and a front view (sectionalview) of FIG. 7B, ribs 21 (see FIG. 6) of the periphery of theprotruding terminals 12 and the metal plate 11 are cut by press or arouter, etc. (step S5). Thus, the wiring substrate 10, in which themetal plate 11 and the protruding terminals 12 are disposed in theintermediate layer and the through holes 13 are bored, can befabricated.

In the wiring substrate 10 according to the embodiment, at least two ofthe plural protruding terminals 12 disposed in the intermediate layerare mutually connected by the joint portion 16, so that it isunnecessary to form the circuit pattern 14 for connecting the twoprotruding terminals 12 on the surface layer, and the circuit pattern onthe surface layer can be reduced. As a result, space of the surfacelayer can be utilized effectively and the space for installing variouselectronic components 15 can be obtained widely.

Also, when the through holes 13 are formed in the protruding terminals12 and the protruding terminals 12 are connected to the circuit pattern14 on the surface layer via the through holes 13, the number of throughholes 13 can be reduced and the space of the surface layer of the wiringsubstrate 10 can be utilized effectively.

Further, the metal plate 11 is used as a conductor and is used forconnection to the circuit pattern 14, so that connection between thecircuit pattern 14 and the metal plate 11 can be easily made by usingthe metal plate 11.

In addition, in the embodiment described above, the example configuredto respectively separate the metal plate 11 from the plural protrudingterminals 12 has been described, but the metal plate 11 itself can alsobe used as an electrode by connecting the metal plate 11 to at least oneprotruding terminal 12 as shown in FIG. 9. In this case, for example,ground connection can easily be made in the case of cabling the circuitpattern 14 by using the metal plate 11 as a ground terminal.

The wiring substrate including the soaking plate and the manufacturingmethod of the wiring substrate of the invention have been describedabove based on the illustrated embodiment, but the invention is notlimited to this, and a configuration of each part can be replaced withany configuration having a similar function.

For example, the embodiment described above has been described by takingthe wiring substrate installed in the electrical distribution box of thevehicle as an example, but the invention is not limited to this, and canbe applied to other wiring substrates.

The present application is based on Japanese Patent Application No.2009-107746 filed on Apr. 27, 2009, the contents of which areincorporated herein by reference.

INDUSTRIAL APPLICABILITY

The invention is extremely useful in effectively using space of asurface layer of a wiring substrate.

REFERENCE SIGNS LIST

10 wiring substrate

11 metal plate

12 protruding terminal

13 through hole

14 circuit pattern

15 electronic component

16 joint

21 rib

25 metal plate

31 prepreg

110 wiring substrate

111 metal plate

112 protruding terminal

113 through hole

114 circuit pattern

115 electronic component

131 prepreg

What is claimed is:
 1. A wiring substrate, comprising: a wiring boardthat has a main face and a side face substantially perpendicular to themain face; a circuit pattern that is formed on the main face of thewiring board; a soaking plate that is disposed in an intermediate layerof the wiring board; and a plurality of protruding terminals that aredisposed in the intermediate layer and are projected outwardly from theside face, wherein the protruding terminals are electrically connectedin the intermediate layer to each other.
 2. The wiring substrateaccording to claim 1, further comprising: other protruding terminal thatis disposed in the intermediate layer and is projected outwardly fromthe side face, wherein the other protruding terminal is separated fromthe plurality of protruding terminals.
 3. The wiring substrate accordingto claim 1, wherein a through hole for electrically connecting theprotruding terminals to the circuit pattern is communicated from themain face to the intermediate layer.
 4. The wiring substrate accordingto claim 1, wherein the soaking plate, which is comprised of aconductive material, is electrically connected to the circuit pattern.